I've already reported that happening to you once before. Just because you're not aware of a reason why/how it would be happening doesn't mean it can't.
The problem isn't that it's throwing girls 'into the lottery' in scramble mode (that wouldn't do anything, Scramble Mode just ignores the lottery's existence), the problem appears to be that it's doing normal mode behavior but giving access to the scramble mode UI which is the undefined behavior.
EDIT: I think I found the cause.
Tested a fix, seems to work but my build is in a limbo state because of other changes needing to be worked with so I do not have an eta on this.
What's happening with the bug is when you start a new game, what it's doing is checking if the toggles for the various game selections are set, and then going forward with those selections. I switched to toggles because there's a third setting in the works and every game-type setting I add would double the number of buttons and so I swapped over to toggles.
What I forgot to do is check to see if a toggle was deactivated in the logic for checking if the toggle was set or not upon starting a gain. So what you're seeing is the abnormal behavior the game does when trying to do scramble+cjs with a low girl-count.